This invention relates to the use and handling of jointed pipe, jointed tubing, and coiled tubing in various well operations. More specifically, the invention relates to the selective handling and running of different types of pipe and tubing in well drilling and well servicing operations, with a universal apparatus incorporating a chain drive tubing injector designed for injecting and pulling jointed tubulars as well as coiled tubing. All jointed tubulars are referred to herein as jointed tubing.
Jointed pipe and jointed tubing are typically run into wells, as drill pipe, production tubing, or casing, during well drilling or servicing operations, using either a drilling rig or a workover rig. Such rigs can be expensive and time consuming to use. To help minimize the time and expense typically involved in using jointed piped or jointed tubing, coiled tubing is sometimes used instead. Various kinds of downhole equipment, such as stabilizers, drill motors, and bits, can be attached to the end of the jointed tubulars or to the coiled tubing, depending upon what type of bottom hole assembly is used.
In early applications of such coiled tubing use, the coiled tubing used was of a relatively small diameter, typically approximately one inch. The use of such small diameter tubing provides the maximum amount of tubing which can possibly be mounted on a reel to be transported to and from the well site. This is important, because the size of the reel which can be transported to the well site is limited by regulations governing the roads over which the reel is to be transported. However, the use of such small diameter coiled tubing limits the flow of fluids therethrough, limits the amount of compression force that can be transmitted through the string of tubing in the well, limits the amount of tension that can be placed on the string of tubing, limits the amount of torque that the tubing can withstand, limits the type and weight of tools that may be used, and even limits the length of tubing that may be used.
Therefore, larger sizes of coiled tubing have come into use, in diameters ranging up to three and one-half inches, or even higher. However, the use of such larger diameter coiled tubing with small reels and handling apparatus designed for the smaller diameter tubing creates problems.
Conventional coiled tubing handling equipment typically comprises a reel of coiled tubing mounted on a platform or vehicle, an injector to run the tubing into and out of the well, a gooseneck permanently affixed to the injector for guiding the coiled tubing between the reel and the injector, a lifting device to support the injector and the gooseneck, a hydraulic power pack to provide power to the reel and the injector and to other hydraulic equipment, and surface equipment such as strippers and blow-out preventors to seal around the coiled tubing as it is run into and out of the well. The vehicle used to transport the reel is typically a trailer or a skid. The reel may be of various sizes, depending upon the size of the coiled tubing to be reeled thereupon, and the length of coiled tubing to be carried. As mentioned above, the reel on which the coiled tubing is shipped is limited primarily by government regulation of roads over which the tubing is to be shipped. Therefore, even large diameter tubing must be shipped on relatively small diameter reels. Typically, the tubing is used at the well site on the same reel on which it was shipped. This can involve repeated reeling and unreeling of large diameter coiled tubing on a small reel, increasing the fatigue from bending stresses.
The lifting device used to support the injector and the gooseneck is typically a hydraulically powered boom or crane located at the rear of the coiled tubing trailer so that it may be located over the well. The hydraulically powered injector has drive chains with tubing grippers located thereon. The drive chains are hydraulically pressed against the tubing to grip the tubing; hydraulically driven sprockets drive the chains to run the tubing into or out of the well. The hydraulic power pack comprises one or more engines driving one or more hydraulic pumps to power the reel, the crane, the injector, and other equipment. Other types of power equipment can also be substituted for hydraulic equipment.
Injectors are known which can handle various diameters of coiled tubing. However, the goosenecks commonly in use are typically designed for relatively small diameter coiled tubing. A typical gooseneck comprises a curved guide member, with the radius of the curve being relatively small, and with the curve covering an arc of approximately ninety degrees (90.degree.) or less. This guide member receives a reach of tubing extending approximately horizontally from the reel, uncoils the tubing from the reel, and guides the tubing between the drive chains of the injector. The gooseneck usually includes a plurality of rollers for supporting the tubing while the tubing is being guided by the gooseneck into the injector. Use of the larger diameters of coiled tubing often results in unnecessary stresses being placed on the tubing by the small radius bends typically found in the goosenecks affixed to injectors.
In known systems, the gooseneck is permanently attached to the injector, and the injector and gooseneck are usually suspended by the crane as a unit, over the well. This requires that the assembly and disassembly of equipment in the bottom hole assembly be accomplished under the suspended injector after the coiled tubing has been run through the gooseneck and the injector. Therefore, the crane must lift the injector and the gooseneck to give workers access to perform the assembly and disassembly of bottom hole equipment. This creates a difficult and sometimes hazardous working environment in a confined area surrounded by well service equipment.
Further, in a servicing application where the well bore is under pressure, introduction of a long bottom hole assembly into the well bore can require a long riser pipe, or lubricator assembly, under the injector for pressure isolation purposes. Where used, the lubricator assembly must be long enough to accommodate the bottom hole assembly, or at least long enough to encompass the external flow ports which may be incorporated into the bottom hole assembly. The bottom hole assembly can be lowered into the lubricator, and the upper and lower lubricator valves are used to isolate the bottom hole assembly, or its external ports, to prevent escape of well bore pressure to atmosphere. Where the bottom hole assembly is long, the lubricator assembly appreciably raises the required height of the working platform, raising the required lift height of the injector and gooseneck over the platform.
In some instances, it is required to use jointed pipe, casing, or tubing, in addition to the coiled tubing, in the work string used in the well. In such cases, it is necessary to use a jack-up frame and power tongs to handle the jointed tubulars, in addition to the coiled tubing handling equipment. Normally, the injector and the gooseneck must be mounted on top of the work deck or platform of the jack-up frame, for running the coiled tubing into or out of the well. When it is desired to run the jointed tubulars on such a rig, the injector and gooseneck must be lifted off the platform by the crane and moved to the side to make room for the jointed tubular handling equipment.
It can be seen, then, that currently known well drilling rigs are typically designed to accommodate the handling of only one type of tubular, and coiled tubing shipping and handling equipment is usually best suited only for the smallest diameters of tubing. This has prevented currently known equipment from being used for a variety of purposes. This singularity of purpose has been exacerbated by the fact that the drilling rig design was determined by a drilling contractor, without any consideration being given to other operations that the owner of the well might wish to undertake. The current need to limit costs associated with gas and oil production has led to the need for the provision of universal equipment which will serve as many diverse needs as possible, and this need is particularly acute in the area of drilling and workover equipment. Modularization of such equipment can contribute to the universality of its application. In particular, a universal drilling apparatus should be composed of replaceable modules, with each module being suited, as far as possible, for the handling and running of jointed tubulars as well as coiled tubing, and with the equipment being suited for handling a variety of diameters of tubing.
In order to improve the efficiency of all types of well drilling and servicing operations, then, it is desirable have a single universal set of equipment which will run jointed tubulars of various diameters, and coiled tubing of various diameters, into and out of a well. Ideally, this universal drilling and well servicing equipment should be composed of replaceable modules, with each module being designed for the handling of jointed tubulars as well as coiled tubing. Additionally, the equipment used to handle such jointed tubulars and coiled tubing must occupy the smallest possible space at the well site, and it should be easily transportable.
In using coiled tubing, it is desirable to minimize the amount of bending and plastic deformation of the tubing during its passage through the gooseneck, to help prevent fatigue failure of the tubing. As tubing is unreeled from the reel, it undergoes a first plastic deformation to a straighter configuration, followed immediately by a second plastic deformation in the curve of the guide member to conform roughly to the radius of the curve of the guide member. This is then immediately followed by a third plastic deformation to a relatively straight configuration as the tubing is fed through the injector. The minimum radius through which coiled tubing should be deformed by the guide member is directly proportional to the diameter of the tubing. As mentioned above, in currently known equipment, the gooseneck mounted on an injector is typically designed for use with relatively small diameter coiled tubing. When large diameter coiled tubing is used with such equipment, excessive bending and plastic deformation of the tubing will occur, resulting in early fatigue failure. This results from the fact that the large diameter tubing is being supported and run into a well through approximately the same path as smaller diameter coiled tubing, using a smaller radius of curvature in the gooseneck. Therefore, the universal drilling and servicing apparatus should minimize the plastic deformation of the coiled tubing, being designed to prolong the life of the largest size tubing anticipated for use with the apparatus.
It is an object of the present invention to provide a drilling and well servicing apparatus capable of injecting and pulling either coiled tubing or jointed tubulars through a typical wellhead assembly, with easy access being provided to assemble and disassemble bottom hole assemblies on either type of tubular. It is a further object of the present invention to provide a drilling and well servicing apparatus for injecting and pulling coiled tubing as well as jointed tubulars, wherein the injector head need not be removed from the wellhead or relocated to allow assembly or disassembly of the bottom hole assembly. It is a still further object of the present invention to provide a drilling and well servicing apparatus for injecting and pulling coiled tubing and jointed tubulars, wherein provision is made for handling a wide variety of diameters of coiled tubing in a way which minimizes fatigue of the tubing resulting from repeated plastic deformation. Finally, it is a yet further object of the present invention to provide a drilling and well servicing apparatus for injecting and pulling coiled tubing and jointed tubulars, wherein injection and retrieval of the tubular is not unduly complicated by use on a pressurized well bore.